Pen



FIG. 1 is an upper front right perspective view of a pen showing my new design;

FIG. 2 is a left side elevation view thereof;

FIG. 3 is a bottom plan view thereof;

FIG. 4 is a front elevation view thereof;

FIG. 5 is a right side elevation view thereof;

FIG. 6 is a top plan view thereof; and,

FIG. 7 is a rear elevation view thereof.

The broken lines shown in FIGS. 3 and 6 are included for the purpose of illustrating environment and form no part of the claimed design. 

The ornamental design for a pen, as shown and described. 